The present invention relates to methods for providing flavor and aroma substances, i.e. flavor additives, for tobacco materials, cigarettes and other smoking articles.
Popular smoking articles, such as cigarettes have a substantially cylindrical rod shaped structure and include a charge of smokable material, such as shreds or strands of tobacco material (i.e., in cut filler form), surrounded by a paper wrapper, thereby forming a tobacco rod. It has become desirable to manufacture a cigarette having a cylindrical filter element aligned in an end-to-end relationship with the tobacco rod. Typically, a filter element includes cellulose acetate tow circumscribed by plug wrap, and is attached to the tobacco rod using a circumscribing tipping material. Many cigarettes include processed tobacco materials and/or tobacco extracts in order to provide certain flavorful characteristics to those cigarettes.
Many types of smoking products and improved smoking articles have been proposed through the years as improvements upon, or as alternatives to, the popular smoking articles. Recently, U.S. Pat. No. 4,708,151 to Shelar; U.S. Pat. No. 4,771,795 to White et al; U.S. Pat. No. 4,714,082 to Banerjee et al; 4,756,318 to Clearman et al; and U.S. Pat. No. 4,793,365 to Sensabaugh, Jr. et al; and European Patent Publication Nos. 212,234 and 277,519 propose cigarettes and pipes which comprise a fuel element, an aerosol generating means physically separate from the fuel element, and a separate mouth end piece. Such types of smoking articles provide natural tobacco flavors to the smoker thereof by heating, rather than burning, tobacco in various forms. Generally, natural tobacco flavors and aromas are important for the taste, aroma, and acceptance of smoking products, including substitute smoking materials. Thus, the search for natural tobacco flavor additives or flavor substances is a continuing task.
For example, U.S. Pat. No. 3,424,171 describes a process for the production of a non-tobacco smokable product having a tobacco taste. Tobacco is subjected to a moderate (i.e. below scorching) heat treatment i.e., at from about 175xc2x0 C. to 200xc2x0 C. (350xc2x0 to 400xc2x0 F.), to drive off aromatic components. These components are trapped on adsorbent charcoal, and removed from the charcoal by solvent extraction. The smokable product disclosed is vegetable matter, treated with the mixture of tobacco aromatic components and the solvent.
Similarly, U.S. Pat. No. 4,150,677 describes a process for the treatment of tobacco which comprises the steps of: (1) contacting tobacco which contains relatively high quantities of desirable flavorants with a stream of non-reactive gas, under conditions whereby the tobacco is heated in a temperature range from about 140xc2x0 to 180xc2x0 C.; (2) condensing the volatile constituents of the resulting gaseous stream; and (3) collecting said condensate. The condensate may be used subsequently to flavor a smoking material in order to enhance the organoleptic qualities of its smoke.
British Patent No. 1,383,029 describes a method of obtaining tobacco aroma substances which comprises an extraction treatment wherein the components of the tobacco that are soluble in a suitable solvent are extracted and the residue is obtained after removing the solvent is subjected to heat treatment at a temperature from 30xc2x0 to 260xc2x0 C.
U.S. Pat. No. 5,038,802 to White et al. and U.S. Pat. No. 5,016,654 to Bernasek et al. disclose extraction processes which heat tobacco and then pass an inert atmosphere through the heating chamber to collect volatiles from the tobacco. The volatiles are then fractionated in downstream operations, which include liquid sorbents, cold temperature traps, and filters.
U.S. Pat. No. 5,235,992 to Sensabaugh proposes a process that involves heating tobacco (e.g., in a flowing gas stream) during a first staged heating to a first xe2x80x9ctoastingxe2x80x9d temperature to drive off volatile materials, increasing the toasting temperature during a second staged heating, and separately collecting, as flavor substances, at least portions of the volatile materials driven off at the first and second toasting temperatures.
U.S. Pat. No. 5,121,757 to White et al. proposes a process for altering the chemical nature of a tobacco extract, in which tobacco material is extracted with a chemical solvent, the extract is contacted with an ammonia compound, and the ammonia-treated extract is subjected to heat treatment in a pressure-controlled environment (e.g., in a Parr bomb).
While these processes have produced flavor substances acceptable for use in many smoking articles, they have either not been suitable for some smoking articles, or have necessarily required the forming of a tobacco extract prior to the obtaining of the desired compound. Additionally, many of these processes necessarily required expensive or inabundant starting materials. It would be highly desirable to provide a process for efficiently and effectively producing flavorful and aromatic compounds useful in the manufacture of smoking articles, which processes in particular could utilize more abundant starting materials and which would not require the additional steps necessary to form tobacco extractions.
It has now been discovered that flavorful and aromatic substances can be produced from tobacco materials previously thought to have little commercial value, for example, tobacco dust from the cigarette manufacturing process, without having to first perform extraction procedures on the materials. Other sources of tobacco dust can be used, such as finely ground tobacco leaves and stems. The flavorful and aromatic substances produced by the invention described herein possess aromatic qualities, total volatile profiles and individual volatile component profiles that are comparable to flavorful and aromatic substances obtained from the more time-consuming and resource-intensive extraction/heat treatment methods of the prior art.
The present invention generally relates to a process for the production of natural tobacco flavor substances useful in tobacco smoking products as flavor substances, and in tobacco substitute materials as a source of tobacco smoke flavor and/or aroma. The process of this invention produces suspensions having a complex mixture of volatile, semi-volatile, and non-volatile aroma/flavor components that are products of the Maillard reactions.
In particular, tobacco in the form of finely divided particles (finely around tobacco material) is produced from tobacco material and is mixed with an aqueous liquid to produce a tobacco suspension. This suspension is subjected to heat treatment in a pressure controlled environment (e.g., a Parr bomb) under conditions sufficient to alter the chemical nature (e.g., the flavor and aroma characteristics) of the finely ground tobacco material. Normally, the tobacco suspension is exposed to a temperature sufficiently high and for a period of time sufficiently long so as to provide an increase in aroma/flavor compounds. However, it is preferable that the tobacco suspension not be exposed to such a high temperature for a sufficiently long period of time so as to provide an aroma/flavor which exhibits a burnt or tarry aroma/flavor.
The finely ground tobacco material can be contacted with an aqueous liquid to comprise a tobacco suspension. The tobacco suspension should have sufficient aqueous liquid such that a liquid phase is present in the suspension. Typically the tobacco suspension can be 80% or less solids. More preferably, the suspension contains less than 50% solids and most preferably contains between 10% and 25% solids. Thus, for the purposes of this invention, it is convenient to refer to the heat treatment, or the moderately high temperature treatment, of a tobacco suspension. For the purposes of the invention, a tobacco suspension can include tobacco material in a dust or powder form contacted with an aqueous liquid further comprising additives (e.g., amino acids, amino acid analogs or amino acid sources or other nitrogen sources, and/or sugar or sugar sources).
Accordingly, the present invention more particularly relates to a process of producing a natural tobacco flavor or aroma by first contacting finely ground tobacco material with an aqueous liquid to provide an aqueous ground tobacco material suspension, which suspension is then subjected to heat treatment at a temperature significantly above about 140xc2x0 C. in a pressure controlled and generally inert environment. In particular, it has been found that the amount of aromatic flavorants generated in the present invention is significantly increased when the temperature of the heat treatment is about 140xc2x0 C. or higher. For example, heat treatment at 175xc2x0 C. can produce about 6 times as much flavorful and aromatic materials as heat treatment at 121xc2x0 C. Preferably the heat treatment is conducted at a temperature of exceeding 140xc2x0 C., more preferably at least about 160xc2x0 C., and most preferably at about 175xc2x0 C.
Typically, the tobacco suspension is heated in a pressure controlled and generally inert environment. Thus, the heat treatment step of the present invention can be conducted in an inert gas or ambient air, and additional oxygen or an equivalent oxidizing agent is not required. In general, the pressure experienced by the ground tobacco material suspension is greater than ambient (i.e., atmospheric) pressure. Typical pressures experienced by the tobacco suspension during the process of the present invention in an enclosed vessel range from about 10 psig to about 1,000 psig, normally from about 20 psig to about 500 psig, preferably exceeding 100 psig.
The ground tobacco material suspension has a tobacco content of at least about 5 percent by weight, preferably at least about 10 percent by weight, and more preferably at least about 25 percent by weight, when the suspension is exposed to the moderately high temperature treatment. For purposes of this invention, the term xe2x80x9ctobacco contentxe2x80x9d relates to the weight of the finely ground tobacco material within the ground tobacco material suspension relative to the total weight of the tobacco suspension.
The resulting flavorful and aromatic compositions are useful as casing or top dressing components for tobacco laminae and cut filler, as well as for other smokable material. Alternatively, such flavorful and aromatic compositions are useful in those types of smoking articles described in U.S. Pat. No. 4,708,151 to Shelar; U.S. Pat. No. 4,714,082 to Banerjee et al.; U.S. Pat. No. 4,756,318 to Clearman et al.; and U.S. Pat. No. 4,793,365 to Sensabaugh; as well as European Patent Publication Nos. 212,234 and 277,519.
The flavorful and aromatic compositions are also useful as cigarette filter additives. For example, the flavorful and aromatic compositions can be incorporated into low density polyethylenes and formed into strands, and then incorporated into cigarette filters as described in U.S. Pat. No. 4,281,671 to Byrne et al. and U.S. Pat. No. 4,862,905 to Green, Jr. et al. The flavorful and aromatic compositions are also useful as cigarette wrapper additives; or as additives to the inner regions of cigarette packages (e.g. within a paper/foil laminate of a cigarette package or within a low density polyethylene film which is placed within a cigarette package) in order to provide a desirable cigarette aroma and xe2x80x9cpack aroma.xe2x80x9d
Flavor compounds produced by the methods of the present invention have organoleptic qualities and volatile content qualities that are comparable to those compounds produced by solvent extraction of natural compounds and heat treatments thereof.
Additionally, it has been found that tobacco materials formerly discarded as waste products of the manufacturing process may be used as starting materials in the process of the present invention to yield flavorful aromatic substances that are also comparative in concentration and desirable organoleptic qualities as other tobacco starting materials. Tobacco dust represents a significant portion of tobacco material lost during the manufacture of cigarettes. The present invention provides a heretofore unknown use for tobacco material as a source for aroma and flavor components for the manufacture of smoking articles and the like.
These and other advantages of the present invention are more completely illustrated in view of the accompanying drawings and detailed description of the invention which follows.